JP6732645B2 - Fixing device and ion irradiation method - Google Patents

Description

The present invention relates to a fixing device for fixing a mask used for ion irradiation to a semiconductor substrate, and an ion irradiation method.

A semiconductor integrated circuit is manufactured by performing various fine processings on a semiconductor substrate such as a silicon wafer. In order to improve the performance of an integrated circuit, a semiconductor substrate may be irradiated with ions such as helium to form a defective region. For example, in a manufacturing process of an insulated gate bipolar transistor (IGBT) including a diode, a mask is used to perform ion irradiation to selectively form a defective region at a portion where the diode is formed. By selectively forming a defect in the diode region, the reverse recovery characteristic of the diode can be improved (for example, see Patent Document 1).

International Publication No. 2011/074075

Several methods have been proposed for fixing the mask to the semiconductor substrate. According to Patent Document 1, the mask is fixed to the substrate by adhesion or bonding. In this case, the mask can be firmly fixed to the substrate, but it is complicated because a chemical treatment such as etching may be required to remove the mask from the substrate.

Alternatively, a removable fastener may be used to secure the mask to the substrate. In that case, reliable fixing is difficult depending on the type and structure of the fastener. Further, with regard to commercially available fasteners, in particular, there may be cases where sufficient fixing force does not work at the target location due to individual differences in fasteners (in other words, variations in quality). As a result, the mask once fixed to the substrate may be displaced from the substrate during the ion irradiation process. If the mask deviates from the position where the mask should be before or during the ion irradiation, the ions are irradiated to an incorrect position on the substrate. This can affect the performance of the device ultimately formed on the substrate. Alternatively, the yield of the ion irradiation process may decrease.

One of the exemplary objects of an aspect of the present invention is to provide a fixing technique for ion irradiation that more reliably holds the position of a mask with respect to a semiconductor substrate.

According to an aspect of the present invention, there is provided a fixing device for fixing the mask to the semiconductor substrate when the semiconductor substrate is irradiated with ions through the mask. The fixing device includes a wafer holder on which the mask and the semiconductor substrate are placed so as to cover the semiconductor substrate with the mask, and the mask and the semiconductor substrate that contact the wafer holder and are not in contact with the side surface of the mask. A fixture for fixing the wafer holder.

According to an aspect of the present invention, there is provided a fixing device for fixing the mask to the semiconductor substrate when the semiconductor substrate is irradiated with ions through the mask. The fixing device includes a wafer holder on which the mask and the semiconductor substrate are mounted so as to cover the semiconductor substrate with the mask, a fixing jig for fixing the mask and the semiconductor substrate to the wafer holder, and a wafer holder mounting surface, And a wafer holder suspension structure configured to guide the wafer holder to the wafer holder mounting surface by the weight of the wafer holder by itself.

According to an aspect of the present invention, a step of placing the mask and the semiconductor substrate on a wafer holder by covering the mask with the semiconductor substrate, and a fixing jig contacting the wafer holder and not contacting a side surface of the mask. A step of fixing the mask and the semiconductor substrate to the wafer holder with the fixing jig; and the wafer holder so that the wafer holder is guided by the weight of the wafer holder on a wafer holder mounting surface of a transfer plate that vertically conveys the wafer holder. An ion irradiation method is provided that includes a step of suspending the carrier plate and a step of irradiating the semiconductor substrate with ions through the mask.

It should be noted that any combination of the above constituent elements and constituent elements and expressions of the present invention that are mutually replaced among methods, devices, systems, etc. are also effective as an aspect of the present invention.

According to the present invention, it is possible to provide a fixing technique for ion irradiation that more reliably holds the position of a mask with respect to a semiconductor substrate.

It is the figure which showed the schematic structure of the ion irradiation system typically. It is a figure which shows an example of a conveyance plate. It is a schematic plan view of the masked wafer according to the embodiment. It is a schematic sectional drawing of the wafer with a mask which concerns on embodiment. It is a schematic plan view of a wafer holder. It is a schematic perspective view which shows a fixing jig. It is an expanded partial sectional view of a fixing jig including a protruding member. It is a schematic plan view of a conveyance plate. It is the schematic which expands and shows a part of conveying plate. It is a schematic plan view which shows a fixing device. It is the schematic which expands and shows the pin hole of a wafer holder. It is a flow chart which shows an example of the ion irradiation method concerning an embodiment.

Hereinafter, modes for carrying out the present invention will be described in detail. Note that the configurations described below are merely examples, and do not limit the scope of the present invention. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. Further, in the drawings referred to in the following description, the size and thickness of each component are for convenience of description, and do not necessarily indicate actual dimensions and ratios.

First, the ion irradiation system 10 that irradiates a semiconductor substrate with ions will be described. FIG. 1 is a diagram schematically showing a schematic configuration of the ion irradiation system 10. The ion irradiation system 10 includes an accelerator 12, a wafer transfer device 14 that holds and transfers a wafer that is a semiconductor substrate, and a beam transport duct 16 that guides the ion beam emitted from the accelerator 12 to the wafer transfer device 14.

The accelerator 12 accelerates the ions and emits them as an ion beam to the outside. As the accelerator 12, for example, a cyclotron type or a van de graph type device is used. The wafer transfer device 14 includes a storage unit (not shown) that stores a plurality of transfer plates 18, an irradiation chamber 20 in which one transfer plate 18 carried from the storage unit is subjected to ion irradiation, a storage unit and an irradiation chamber 20. And a moving mechanism 22 that moves the transport plate 18 between and. The carrier plate 18 can carry a plurality of wafers. In the irradiation chamber 20, these wafers are irradiated with an ion beam. A vacuum pump that maintains a vacuum inside, an electromagnetic coil that corrects the direction of the beam, and the like are provided in the middle of the beam transport duct 16.

The ion irradiation system 10 is configured to be able to adjust various parameters related to the ion beam, such as ion species, acceleration energy, ion irradiation amount (beam current, irradiation time), and ion irradiation direction. Examples of the ion species used for ion irradiation include those in which at least one atom selected from the group consisting of H, He, B, C, N, O, Ne, Si, Ar, Kr, and Xe is ionized. .. Specific examples thereof include ¹ H ⁺ , ² H ⁺ , ³ He ²⁺ , ⁴ He ^{2+ and the} like. The ion irradiation system 10 may perform ion irradiation with acceleration energy of 0.001 MeV or more. Alternatively, the acceleration energy may be 0.1 MeV or more. Ion irradiation may be performed with an acceleration energy of 100 MeV or less. Alternatively, the acceleration energy may be 30 MeV or less.

The wafer irradiated with ions is typically a circular silicon wafer, but the shape and material of the wafer are not limited to this. The circular wafer has a diameter of, for example, within 300 mm, and may have a diameter of, for example, 300 mm or 250 mm or 200 mm or 150 mm. The circular substrate W may have a thickness of, for example, 0.05 mm to 1.50 mm.

When the wafer is irradiated with ions, the ions reach a certain depth inside the wafer. At that time, lattice defects are formed in the vicinity including the reached region, and the regularity (periodicity) of the crystal is disturbed. Electrons are more likely to be scattered in such a region having many lattice defects, which hinders the movement of electrons. That is, the resistivity increases in the region where the local lattice defect is generated by the ion irradiation. By adjusting the above parameters in the ion irradiation system 10, the in-plane position, the depth position, the width in the depth direction, and the magnitude of the resistivity of the defect layer in the wafer can be appropriately set. The defect layer obtained by ion irradiation can be used for various purposes such as the purpose of forming a carrier lifetime control layer in addition to the purpose of forming a high resistance region.

FIG. 2 is a diagram showing an example of the transport plate 18. The carrier plate 18 is configured to stand and carry a plurality of wafer holders 24 for ion irradiation. These wafer holders 24 are horizontally arranged in a line and held at respective predetermined positions on the carrier plate 18.

As will be described later in detail, each wafer holder 24 is configured such that the mask 25 is placed over the wafer 26 (that is, the mask 25 is on the outside and the wafer 26 is on the inside so that the mask 25 and the wafer 26 overlap each other). 26 can be placed. The mask 25 and the wafer 26 can be fixed to the wafer holder 24 by a fixing jig (described later), a clip, or other fastener. Thus, the wafer holder 24 forms a masked wafer. The carrier plate 18 can carry a plurality of wafers with masks.

The mask 25 is a disk-shaped member having a size capable of covering the wafer 26. The mask 25 is a metal containing aluminum (Al), stainless steel (SUS), nickel (Ni), tungsten (W), molybdenum (Mo), titanium (Ti) and alloys thereof, silicon (Si) and other resins. Etc. However, the shape and material of the mask 25 are not limited to this. For example, when the wafer 26 has a rectangular or other planar shape, the mask 25 may also have a planar shape adapted to this. Further, the mask 25 may have an opening for passing the irradiated ions and an alignment opening provided for alignment.

The moving mechanism 22 is configured to move the transport plate 18 at least in the horizontal direction. The moving mechanism 22 can move the carrier plate 18 so that all the wafers 26 mounted on the carrier plate 18 are sequentially irradiated with the ion beam. Then, when the ion irradiation process is completed, the moving mechanism 22 engages the shaft end portion 28a of the transport shaft 28 with the engaged portion 30 provided at the end portion of the transport plate 18, and moves the transport plate 18. Return it to the storage unit. Then, the moving mechanism 22 carries the next transport plate 18 into the irradiation chamber 20.

The wafer holder 24 is supported by the transfer plate 18 so as to stand vertically to the horizontal plane. The mask 25 and the wafer 26 fixed to the wafer holder 24 are also supported by the transfer plate 18 in a state of standing vertically to the horizontal plane. The ion beam is incident on the mask 25 along the horizontal plane and is applied to the wafer 26 via the mask 25. If necessary, the transfer plate 18 may be configured to transfer the wafer holder 24, the mask 25, and the wafer 26 while standing upright with respect to the horizontal plane.

FIG. 3 is a schematic plan view of the masked wafer according to the embodiment. The wafer 26 is covered with the mask 25 placed on the wafer holder 24 as described above. An alignment mark may be provided on the irradiation surface of the wafer 26. The mask 25 and the wafer 26 are fixed to the wafer holder 24 so that the alignment mark and the alignment opening of the mask 25 are aligned with each other.

The fixing device 32 shown in FIG. 3 includes a plurality of fixing jigs 34 for fixing the mask 25 and the wafer 26 to the wafer holder 24 in addition to the above-mentioned wafer holder 24. Two fixing jigs 34 are attached to both sides of the wafer holder 24 with the center C interposed therebetween. One fixing jig 34 is on the upper side 24a when the wafer holder 24 is stood up, and the other fixing jig 34 is on the lower side 24b. The two fixing jigs 34 are located at both ends of the diameter of the mask 25 and the wafer 26. Further, the fixing jig 34 is provided with a protruding member 35 described later.

The wafer holder 24 comprises an extension 36 outside the mask 25 (more precisely outside the area occupied by the mask 25 by design). The expanded portion 36 extends to the left and right of the wafer holder 24 and is divided into a left side area 36a and a right side area 36b with the arrangement location of the fixing jig 34 as a boundary. An opening 38 is provided near the upper side 24a in the left side region 36a. The left side region 36a has an elongated portion 40 that extends radially outward (upper left portion of the wafer holder 24) from the opening 38. The elongated portion 40 can be used by a worker as a handle for the wafer holder 24.

Further, the wafer holder 24 is provided with a plurality of pin holes 42. One of the two pin holes 42 is formed in the right side region 36b near the upper side 24a, and the other pin hole 42 is formed in the left side region 36a near the lower side 24b. The two pin holes 42 are located equidistant from the center C of the wafer holder 24. In this way, the pin holes 42 are arranged diagonally in the expanded portion 36 of the wafer holder 24.

FIG. 4 is a schematic cross-sectional view of the masked wafer according to the embodiment. FIG. 4 shows an AA cross section shown in FIG. FIG. 5 is a schematic plan view of the wafer holder 24. FIG. 5 shows the wafer holder 24 in a state where the mask 25 and the wafer 26 are not placed. FIG. 6 is a schematic perspective view showing the fixing jig 34. FIG. 7 is an enlarged partial sectional view of the fixing jig 34 including the protruding member 35.

The wafer holder 24 has a bottom portion 24c and an outer frame portion 24d. For convenience of explanation, the outer peripheral portion of the wafer holder 24 is referred to as the above-mentioned expanded portion 36 and outer frame portion 24d. However, the wafer holder 24 is actually an integral plate-shaped member having the expansion portion 36, the outer frame portion 24d and the bottom portion 24c. The expanded portion 36 is outside the mask 25 in plan view when the mask 25 is fixed to the wafer holder 24 by the fixing jig 34, and the outer frame portion 24d is covered by the fixing jig 34 or the mask 25. The left side region 36a and the right side region 36b of the expansion portion 36 are connected by the outer frame portion 24d.

The mask 25 has a mask front surface 25 a facing the side opposite to the wafer holder 24 and irradiated with an ion beam, and a mask back surface 25 b facing the wafer front surface 25 a and facing the wafer 26. Further, the mask 25 has a mask side surface 25c that connects the mask front surface 25a to the mask back surface 25b and defines the outer shape of the mask 25.

The wafer 26 has a wafer front surface 26a facing the mask back surface 25b and irradiated with an ion beam, and a wafer back surface 26b facing the wafer front surface 26a and facing the wafer holder 24. The wafer 26 also has a wafer side surface 26c that connects the wafer front surface 26a to the wafer back surface 26b and defines the outer shape of the wafer 26.

The fixing device 32 further includes a spacer member 44 arranged between the outer peripheral region of the wafer 26 and the mask 25. The spacer member 44 is a ring-shaped member corresponding to the outer diameter of the wafer 26. The spacer member 44 contacts the outer peripheral area of the wafer front surface 26a and the outer peripheral area of the mask rear surface 25b. The spacer member 44 has a role of making the mask back surface 25b and the wafer front surface 26a non-contact with each other. The upper surface of the spacer member 44, which is in contact with the mask back surface 25b, has the same height as the outer frame portion 24d of the wafer holder 24. Alternatively, the upper surface of the spacer member 44 may be slightly higher than the outer frame portion 24d of the wafer holder 24 for reliable transmission of the fixing force. The spacer member 44 has a thickness of, for example, about 0.5 mm to 2 mm.

The outer diameter of the spacer member 44 is equal to the outer diameter of the wafer 26. However, the outer diameter of the spacer member 44 may be different from the outer diameter of the wafer 26. For example, the outer diameter of the spacer member 44 may be larger than the outer diameter of the wafer 26 and smaller than the outer diameter of the mask 25.

Further, the wafer holder 24 has a wafer holder recess 46 capable of accommodating the wafer 26 defined by the bottom portion 24c and the outer frame portion 24d. The wafer holder recess 46 has an opening having a size corresponding to the outer diameter of the wafer 24, and the wafer side surface 26c is in contact with the outer frame portion 24d or surrounded by a slight gap from the outer frame portion 24d. The wafer holder recess 46 has a depth of, for example, about 1 mm to 5 mm.

The wafer holder concave portion 46 is provided with a wafer holder convex portion 48 adjacent to the bottom portion 24c of the wafer holder 24 and the outer frame portion 24d and integrally formed with them. The wafer holder protrusion 48 is formed in a ring shape corresponding to the outer diameter of the wafer 26. The wafer holder convex portion 48 is provided as another spacer member in contact with the outer peripheral region of the wafer back surface 26b. The wafer holder convex portion 48 has a role of making the wafer back surface 26b and the bottom portion 24c of the wafer holder 24 out of contact with each other. The wafer holder protrusion 48 has a height of, for example, about 0.5 mm to 2 mm.

Here, the outer peripheral area of the wafer 26 is an area of about 1 mm to 3 mm from the wafer side surface 26c, and is generally an area where no semiconductor device is formed. Therefore, even if the spacer member 44 or the wafer holder convex portion 48 contacts the wafer 26 in the wafer outer peripheral region, the influence on the semiconductor device formed on the wafer 26 is small. Further, by providing the spacer member 44 and the wafer holder convex portion 48, it is possible to prevent the mask 25 and the wafer holder 24 from coming into contact with the wafer inner region where the semiconductor device is generally formed and damaging the wafer inner region. ..

The outer frame 24d of the wafer holder 24 is formed with a protrusion 24e that fits the notch of the wafer 26 at the lowermost portion (that is, the portion closest to the fixing jig 34 on the lower side 24b side) (see FIG. 5). The protrusion 24e is provided as a mark for rough position adjustment (also referred to as rough adjustment) when the wafer 26 is placed on the wafer holder 24. When the wafer holder 24 is erected, the notch of the wafer 26 fits into the protrusion 24e due to gravity. This is useful for stabilizing the posture of the wafer with a mask and at the time of ion irradiation. Note that the illustration of the protrusion 24e is omitted in FIG.

The fixing jig 34 has a U-shape or a lateral U-shape, and sandwiches the outer peripheral portions of the mask 25 and the wafer holder 24, respectively. More specifically, the fixing jig 34 includes a wafer holder side arm 50 and a mask side arm 52 extending along the wafer holder side arm 50, and sandwiches the mask 25, the wafer 26, and the wafer holder 24 between both arms. Is configured. The fixing jig 34 also includes an arm connecting portion 54 that connects the wafer holder side arm 50 to the mask side arm 52. The fixing jig 34 fixes the mask 25 and the wafer 26 to the wafer holder 24 so that the mask 25 and the wafer 26 are not displaced in the in-plane direction, and a laminated body including the mask 25, the spacer member 44, the wafer 26, and the wafer holder 24 is formed.

The above-mentioned protruding member 35 is provided on the mask-side arm 52 and can protrude toward the mask 25. The protruding member 35 is arranged directly above the spacer member 44 so as to abut the mask 25. Accordingly, the fixing jig 34 can firmly sandwich the wafer 26 and the spacer member 44 between the mask 25 and the wafer holder 24. Therefore, the positional displacement between the mask 25 and the wafer 26 can be prevented.

The mask side arm 52 has a screw hole 52a. The protruding member 35 includes a protruding member main body 35a that is a screw that is screwed into the screw hole 52a, and a protruding member tip 35b that abuts on the mask front surface 25a. When the projecting member 35 is rotated with respect to the mask side arm 52 as indicated by an arrow 62, the projecting member 35 projects toward the mask 25 by screwing with the screw hole 52a, and when it is rotated in the opposite direction, the projecting member 35 is masked. Move away from 25.

The protruding member tip 35b is supported by the protruding member body 35a so as to be rotatable with respect to the protruding member body 35a. A recess is formed at the lower end of the protruding member body 35a. The protruding member tip 35b has a corresponding hemispherical surface and is fitted into the recess of the protruding member main body 35a. The protruding member tip 35b is slidable with respect to the concave portion of the protruding member main body 35a. The surface of the protruding member tip 35b opposite to the hemispherical surface is a flat surface. This plane abuts the mask front surface 25a when the protruding member 35 protrudes from the mask side arm 52. When the tip 35b of the protruding member contacts the front surface 25a of the mask, the tip 35b of the protruding member is stopped by the frictional force with the front surface 25a of the mask.

Since the protruding member tip 35b can rotate independently of the protruding member main body 35a, it is possible to prevent or reduce the positional deviation between the mask 25 and the wafer 26 due to the screw rotation. Further, since the protruding member tip 35b is in surface contact with the mask front surface 25a, the fixing force per unit area acting on the mask 25 from the protruding member 35 is smaller than in the case of point contact. Therefore, it is possible to prevent or reduce damage to the mask 25 that may occur when the protruding member 35 is brought into contact with the mask 25.

The fixing jig 34 fixes the mask 25 and the wafer 26 to the wafer holder 24 so as to be in contact with the wafer holder 24 and not in contact with the mask side surface 25c. Therefore, the wafer holder 24 is provided with a fixing jig mounting portion, for example, a cutout portion 56, which is formed so that the fixing jig 34 is mounted on the wafer holder 24 without contacting the mask side surface 25c.

The cutout portion 56 has a fixing jig contact surface 58 located radially outside of the designed position of the mask side surface 25c. The fixing jig abutting surface 58 contacts the inner surface of the arm connecting portion 54 to position the fixing jig 34 in the radial direction of the wafer holder 24. Therefore, the fixing jig 34 does not contact the mask side surface 25c, and a gap 59a is formed between the arm connecting portion 54 and the mask side surface 25c. Therefore, when the fixing jig 34 is mounted, the fixing jig 34 does not push the mask 25, and the displacement of the mask 25 due to it does not occur.

Further, the fixing jig 34 does not contact the mask front surface 25a except for the protruding member 35. A gap 59b is also formed between the lower surface of the mask side arm 52 and the mask front surface 25a. When the fixing jig 34 is mounted, the fixing jig 34 is inserted into the notch 56 while the wafer holder side arm 50 of the fixing jig 34 is applied to the wafer holder 24, so that the fixing jig 34 does not come into contact with the mask 25 at all. Can be installed.

In order to facilitate this mounting work, the wafer holder side arm 50 is longer than the mask side arm 52. The extension length of the wafer holder side arm 50 from the arm connection portion 54 is larger than the extension length of the mask side arm 52 from the arm connection portion 54. First, the extended portion of the wafer holder side arm 50 can be abutted against the notch 56 from the bottom 24c side of the wafer holder 24, and then the fixing jig 34 can be inserted radially inward.

The cutout portion 56 further includes a pair of fixing jig guide surfaces 60 extending radially outward from both sides of the fixing jig contact surface 58. The fixing jig guide surface 60 connects the fixing jig contact surface 58 to the upper side 24a (or the lower side 24b). These fixing jig guide surfaces 60 guide the arm connecting portion 54 in the radial direction of the wafer holder 24 along both sides of the arm connecting portion 54 when the fixing jig 34 is inserted into the cutout portion 56. Since the mounting location of the fixing jig 34 is set in advance in this manner, the mounting work is easy.

The expanded portion 36 of the wafer holder 24 extends radially outward from the fixing jig contact surface 58. The diameter of the wafer holder 24 is larger than that of the mask 25 over the entire circumference. In this way, the wafer holder 24 has an extra region outside the mask 25 in which the pin hole 42 and the elongated portion 40 serving as a handle are provided. The operator can perform operations such as setting the wafer holder 24 on the transfer plate 18 and removing the wafer holder 24 from the transfer plate 18 with the surplus area. Since it is not necessary to touch the mask 25 during the work, there is less possibility of accidentally touching the mask 25 and causing positional displacement.

FIG. 8 is a schematic plan view of the transport plate 18. FIG. 9 is a schematic view showing a part of the transport plate 18 in an enlarged manner. FIG. 10 is a schematic plan view showing the fixing device 32. FIG. 10 shows a state in which the masked wafer according to the embodiment is set on the carrier plate 18. FIG. 11 is an enlarged schematic view showing the pin hole 42 of the wafer holder 24.

In addition to the engaged portion 30 described above, the transport plate 18 includes a wafer holder mounting surface 64 and a plurality of inversely tapered pins 66 provided on the wafer holder mounting surface 64. The wafer holder mounting surface 64 is provided on the carrier plate 18 as a plane for positioning the wafer holder 24 at a fixed position by contact with the wafer holder 24 (specifically, the bottom portion 24c of the wafer holder 24 shown in FIG. 4).

The plurality of pins 66 are provided in the number and arrangement corresponding to the pin holes 42 of the wafer holder 24. Therefore, the two pins 66 are arranged diagonally. The pin 66 has an inverted conical shape that is erected from the pin pedestal 68 on the small disc. The pin pedestal 68 is provided on the wafer holder mounting surface 64 and fixes the root of the pin 66. The pins 66 are erected perpendicularly to the wafer holder mounting surface 64.

Further, the transport plate 18 is provided with an opening 70. The opening 70 is formed in the carrier plate 18 for receiving the fixing jig 34 when the wafer holder 24 contacts the wafer holder mounting surface 64. Therefore, the carrier plate 18 can stand and carry the wafer holder 24 to which the fixing jig 34 is attached.

The fixing device 32 includes a wafer holder suspension structure 72 configured such that the wafer holder 24 is guided to the wafer holder mounting surface 64 by the weight of the wafer holder 24. The wafer holder suspension structure 72 includes the above-described pin 66 and the pin hole 42 of the wafer holder 24. The pin 66 has the thickest tip and is gradually thinned toward the pin base 68. Therefore, when the pin hole 42 of the wafer holder 24 is hooked on the pin 66, the wafer holder 24 moves downward due to its own weight in accordance with the reverse taper surface (that is, the reverse conical surface) of the pin 66 and approaches the transfer plate 18, and finally the wafer holder mounting is performed. Hit the placing surface 64. Therefore, the wafer holder 24 can be quickly attached to the transfer plate 18. In addition, the masked wafer can be reliably positioned at a fixed position. Further, since the wafer holder 24 is supported by the two pins 66 arranged diagonally, the position is stable even during the transportation by the transportation plate 18.

The pin hole 42 of the wafer holder 24 has a so-called Dharma hole shape. The pin hole 42 has a first arc-shaped contour 42a and a second arc-shaped contour 42b. Both ends of the first arc-shaped contour 42a are connected to both ends of the second arc-shaped contour 42b. The first arcuate contour 42a has a first center 74 and a first radius 75, and the second arcuate contour 42b has a second center 76 and a second radius 77. The second center 76 is eccentric downward from the first center 74, so that the second arc-shaped contour 42b is displaced downward from the first arc-shaped contour 42a. The pin hole 42 is line-symmetric with respect to a straight line 78 connecting the first center 74 and the second center 76. The second radius 77 is larger than the first radius 75. The first radius 75 is smaller than the radius of the tip of the pin 66 and larger than the radius of the root of the pin 66. The second radius 77 is larger than the radius of the tip of the pin 66.

Therefore, the pin 66 can be inserted into the second arc-shaped contour 42b of the pin hole 42. Then, the pin 66 fits into the first arc-shaped contour 42a by the weight of the wafer holder 24. With such shapes of the pins 66 and the pin holes 42, it is possible to prevent the masked wafer from falling off during transportation and suppress vibration. Further, when recovering the masked wafer after the ion irradiation from the transfer plate 18, it can be easily removed by slightly lifting the wafer holder 24.

FIG. 12 is a flowchart showing an example of the ion irradiation method according to the embodiment. First, an operator prepares a semiconductor substrate and a mask respectively (S10) and positions the semiconductor substrate and the mask in close proximity to each other (S12). Then, the semiconductor substrate and the mask are fixed to the wafer holder by a fixing jig (S14), and the masked wafer is set on the carrier plate (S16). Ion irradiation is performed on the wafer with a mask (S18). The masked wafer is collected from the carrier plate (S20), and it is confirmed whether the semiconductor substrate after the ion irradiation and the mask are aligned (S22). Then, the fixation of the semiconductor substrate and the mask is released (S24).

At the start of work, the wafer holder is placed horizontally on the workbench. The operator places the mask and the semiconductor substrate on the wafer holder so as to cover the semiconductor substrate with the mask. The semiconductor substrate and the mask are aligned. The mask and the semiconductor substrate are fixed to the wafer holder by the fixing jig so that the fixing jig is in contact with the wafer holder and is not in contact with the side surface of the mask. The wafer holder is hung on the transfer plate so that the wafer holder is guided by the weight of the wafer holder on the wafer holder mounting surface of the transfer plate that vertically conveys the wafer holder. Ions are irradiated to the semiconductor substrate through a mask.

The operator does not touch the mask between the time the mask and the wafer are fixed and the time the fixing is released. Therefore, the operator does not accidentally shift the mask from the desired position. Therefore, the position of the mask with respect to the semiconductor substrate can be reliably held.

The present invention has been described above based on the embodiments. It is understood by those skilled in the art that the present invention is not limited to the above-described embodiment, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present invention. By the way.

10 ion irradiation system, 18 transfer plate, 24 wafer holder, 25 mask, 26 wafer, 32 fixing device, 34 fixing jig, 35 protruding member, 35a protruding member main body, 35b protruding member tip, 36 expanded portion, 42 pin hole, 42a First arc-shaped contour, 42b Second arc-shaped contour, 44 Spacer member, 50 Wafer holder side arm, 52 Mask side arm, 52a Screw hole, 58 Fixing jig contact surface, 64 Wafer holder mounting surface, 66 pin, 72 Wafer holder Suspension structure, 74 1st center, 75 1st radius, 76 2nd center, 77 2nd radius.

Claims (10)

A fixing device for fixing the mask to the semiconductor substrate when ion-irradiating the semiconductor substrate through the mask,
A wafer holder on which the mask and the semiconductor substrate are placed so as to cover the semiconductor substrate with the mask;
A fixing jig for fixing the mask and the semiconductor substrate to the wafer holder so as to be in contact with the wafer holder and not in contact with the side surface of the mask;
A spacer member arranged between the outer peripheral region of the semiconductor substrate and the mask ,
The fixing jig includes a wafer holder side arm and a mask side arm extending along the wafer holder side arm, and is configured to sandwich the mask, the semiconductor substrate, and the wafer holder between both arms.
The mask-side arm is provided with a projecting member which can protrude toward the mask, the protrusion member is fixed and wherein that you have been arranged so as to impinge on the mask at immediately above the spacer member. 2. The fixing device according to claim 1, wherein the wafer holder includes a fixing jig contact surface located radially outward of a designed position of a side surface of the mask placed on the wafer holder. The fixing device according to claim 2, wherein the wafer holder includes an expansion portion that extends outward in the radial direction from the fixing jig contact surface. The mask-side arm has a screw hole, the protruding member includes a protruding member main body that is a screw screwed into the screw hole, and a protruding member tip that abuts the mask, the protruding member tip, The fixing device according to claim 1 , wherein the fixing device is supported by the protruding member main body so as to be rotatable with respect to the protruding member main body. A carrier plate which has a wafer holder mounting surface and which vertically conveys the wafer holder on which the fixing jig is mounted,
Fixing device according to any one of 4 from claim 1, further comprising a, a wafer holder suspended structure configured to the wafer holder is guided by the wafer holder mounting surface by the weight of the wafer holder. The fixing device according to claim 5 , wherein the wafer holder suspension structure includes an inversely tapered pin provided on the wafer holder mounting surface and a pin hole provided in the wafer holder. The pin hole has a first arcuate contour having a first center and a first radius, a second center eccentric downward from the first center and a second radius larger than the first radius. A second arcuate contour connected to the arcuate contour, the fixation device of claim 6 . A fixing device for fixing the mask to the semiconductor substrate when ion-irradiating the semiconductor substrate through the mask,
A wafer holder on which the mask and the semiconductor substrate are placed so as to cover the semiconductor substrate with the mask;
A fixture for fixing the mask and the semiconductor substrate to the wafer holder,
A carrier plate which has a wafer holder mounting surface and which vertically conveys the wafer holder on which the fixing jig is mounted,
A wafer holder suspension structure configured to guide the wafer holder to the wafer holder mounting surface by its own weight .
The wafer holder suspension structure, the fixing device, wherein the reverse tapered pin provided on the wafer holder mounting surface, the Rukoto and a pin hole formed in the wafer holder. Placing the mask and the semiconductor substrate on a wafer holder by covering the semiconductor substrate with the mask;
Fixing the mask and the semiconductor substrate to the wafer holder with the fixing jig so that the fixing jig is in contact with the wafer holder and is not in contact with the side surface of the mask;
A step of suspending the wafer holder on the transfer plate so that the wafer holder is guided by the weight of the wafer holder to a wafer holder mounting surface of a transfer plate that vertically conveys the wafer holder;
Irradiating the semiconductor substrate with ions through the mask ,
The step described above comprises disposing a spacer member between the peripheral region of the semiconductor substrate and the mask,
The fixing jig includes a wafer holder side arm and a mask side arm extending along the wafer holder side arm, and is configured to sandwich the mask, the semiconductor substrate, and the wafer holder between both arms.
The mask-side arm is provided with a projecting member which can protrude toward the mask, the projection member, ion irradiation method characterized that you have been arranged so as to impinge on the mask at immediately above the spacer member. Placing the mask and the semiconductor substrate on a wafer holder by covering the semiconductor substrate with the mask;
Fixing the mask and the semiconductor substrate to the wafer holder with a fixing jig;
A step of suspending the wafer holder on the transfer plate so that the wafer holder is guided by the weight of the wafer holder to a wafer holder mounting surface of a transfer plate that vertically conveys the wafer holder;
Irradiating the semiconductor substrate with ions through the mask,
An inversely tapered pin is provided on the wafer holder mounting surface, and a pin hole is provided in the wafer holder,
In the suspending step, the ion irradiation method is characterized in that the wafer holder is suspended on the transfer plate by inserting the pin into the pin hole.

Images